EP2664506A1 - Vehicle with a hydrostatic traction drive - Google Patents

Abstract

The vehicle (1) has a hydrostatic traction drive (2) comprising a hydrostatic gearbox (4) that is arranged in a drive train. The traction drive provides a function of an inch brake that is actuatable independent of a service brake (3). A trailer (7) is coupled with the vehicle and actuatable by a trailer brake (8) on the vehicle. An inch braking process triggers a predetermined trailer braking process in a predetermined operation mode. An electrical sensor arrangement (10) is attached to a brake control element (9) for sensory acquisition of deflection (A) of the control element. The electrical sensor arrangement comprises an absolute sensor e.g. potentiometer and magnetoresistive (MR) sensor, or an incremental sensor i.e. hall sensor. Independent claims are also included for the following: (1) a full trailer combination (2) a method for operating a vehicle.

Description

The present invention relates to a vehicle with a hydrostatic drive according to the preamble of claim 1, a truck with such a vehicle and at least one trailer coupled to the vehicle according to the preamble of claim 14 and a method for operating such a vehicle with a hydrostatic drive according to the preamble of claim 15.

In the case of the vehicle in question with a hydrostatic drive, in the present case the scope of application of mobile agricultural machines is in the foreground, which is not to be understood as limiting. Such machines are, for example, tractors, farm loader, in particular telehandlers, but also to self-propelled harvesters o. Like ..

The well-known vehicle ( EP 2 384 941 A1 ), from which the invention proceeds, is equipped in the usual way with a hydrostatic drive and a service brake. The traction drive has a Hydrostatgetriebe with Hydrostatic pump and Hydrostatmotor, which are arranged in a closed hydraulic circuit. The Hydrostatpumpe is regularly driven by a diesel engine. The hydrostatic transmission is a transmission with infinitely variable speed ratio (CVT). The setting of the speed ratio is carried out here by a corresponding adjustment of the displacement of the Hydrostatpumpe or the Hydrostat motor.

The hydrostatic transmission of the above vehicle provides the known function of an "inching" brake, which is essentially due to the braking action of the diesel engine. The operation of the inching brake is done by a corresponding change in the speed ratio of the hydrostatic transmission, in such a way that the diesel engine is driven during the inching braking via the drive train and acts correspondingly braking.

In order to use the known vehicle for transport tasks, can be coupled to the vehicle a trailer. The trailer is equipped with a trailer brake which can be actuated by the vehicle, the brake circuit of which is supplied to the vehicle via the brake circuit of the service brake when the trailer is coupled to the vehicle.

In the EP 2 384 941 A1 It has already been recognized that actuation of the inch brake is in principle associated with an undesirable pushing the trailer onto the vehicle, even before the service brake and thus the trailer brake comes into action. Accordingly, there is proposed to detect an already carried on pushing the trailer to the vehicle sensory and to trigger a targeted actuation of the trailer brake as a function of this detection.

A disadvantage of the known vehicle is the fact that there can only be reacted to the in itself undesirable sliding of the trailer. The solution proposed there can therefore only represent a legal compromise.

The invention is based on the problem of designing and further developing the known vehicle in such a way that the trailer is prevented from being pushed onto the vehicle, in particular during inching braking, with simple structural means.

The above problem is solved in a vehicle according to the preamble of claim 1 by the features of the characterizing part of claim 1.

What is essential is the general idea that suspending the trailer onto the vehicle during inching braking can be most effectively avoided by already initiating the inching braking as such a predetermined trailer braking even when the service brake has not yet been applied. The proposed relationship between Inchbremsung and trailer braking can be provided permanently or only in a predetermined operating mode.

The term "inching" here includes all sub-operations occurring in the context of the overall operation of inching braking, with a view to triggering trailer braking. Each of these sub-operations of inching braking may, according to the proposal, determine the triggering time and the course of trailer braking. These include, for example, the inching operation by means of a brake control element, the activation of the hydrostatic pump or of the hydrostatic motor or the braking action which is physically generated during inching.

When designing the term "inching braking", it should also be taken into consideration that the control of the hydrostatic pump or of the hydrostatic motor and / or the physically generated braking effect can be varied in terms of control technology for a given inching operation. For example, the braking control of the Hydrostatpumpe or the Hydrostat motor can be reduced when an overload of the hydrostatic transmission threatens. This can for example be the case when driving off a steep gradient. Thus, in extreme cases, inch braking in the present sense may involve a strong inching operation by means of a brake control element, but only a weak or even no braking control of the hydrostatic pump or hydrostatic motor. Nevertheless, it is proposed that the trailer braking be triggered depending on the inching operation as stated above.

In the preferred embodiment according to claim 2, the inch brake trailer brake is at least in phase in a substantially proportional relation to the initiating inch braking, in particular to a corresponding operator side inching operation. This takes into account, in particular, the fact that inching of a certain size should be countered by trailer braking of an appropriate size to ensure that the trailer and trailer trailer remains stretched.

For operator side Inchbetätigung preferably a brake control is provided, which is associated with an electrical sensor assembly (claim 3). In a preferred variant, the basis for the above proportional relationship is the displacement the brake control element, which constructively and control technology leads to a simple implementation.

In the particularly preferred embodiment according to claim 4, a sensor arrangement for sensory detection of the above deflection of the brake control element is provided, which is evaluated according to claim 5 of the vehicle control. The vehicle control triggers the respective trailer braking after a predetermined transfer function. Thus, the determination of the trailer braking is easily adaptable to a variety of boundary conditions.

The preferred embodiment according to claim 6 relates, for example, to the selection of a transfer function from a number of stored transfer functions or the parameterization of a possibly selected transfer function, in each case depending on at least one brake-relevant influencing factor. This makes it possible to fully exploit the possibilities of the control technology implementation of the proposed solution. In particular, it is possible to use the current trailer load as a brake-relevant influencing factor (claim 7).

In the further preferred embodiments according to claims 8 and 9 is a user-side service braking by the service brake always preceded by an inch braking and thus a corresponding trailer braking. This ensures that the trailer is already braked before the much stronger service braking takes place when compared with the inching brake with appropriate operation.

In the further preferred embodiment according to claim 10 also initiates a service brake as such a predetermined trailer braking, wherein the service brake related trailer braking is triggered independently of the inch brake related trailer braking. Due to this independence, the trailer braking can be controlled optimally depending on the operator-operated brake. The term "service braking" in this context is to be interpreted as far as the above-explained term "inching".

According to a further teaching according to claim 14, which has independent significance, a trailer is claimed with a proposed vehicle and with at least one trailer coupled to the vehicle. Reference may be made to all versions of the proposed vehicle that are suitable for describing the trailer as a whole.

According to another teaching according to claim 15, which also has independent significance, a method for the operation of a proposed vehicle is claimed. Also in this regard may be made to all versions of the proposed vehicle.

Fig. 1

an der Bremsung eines vorschlagsgemäßen Fahrzeugs und eines daran angekoppelten Anhängers beteiligte Komponenten einschließlich der zugeordneten funktionalen Zusammenhänge,

Fig. 2

an der inchbremsenbedingten Anhängerbremsung beteiligten Komponenten des Fahrzeugs und Anhängers gemäß Fig.1 einschließlich der zugeordneten elektro-hydrostatischen Verbindungen,

Fig. 3

eine vorschlagsgemäße Abhängigkeit der Anhängerbremsung von der Auslenkung des Brems-Bedienelements eines vorschlagsgemäßen Fahrzeugs gemäß Fig. 1 in einer ganz schematischen Ansicht.

In the following, we will explain the invention with reference to a purely exemplary embodiment illustrative drawing. In the drawing shows:

Fig. 1

components involved in the braking of a proposed vehicle and a trailer attached thereto, including the associated functional relationships,

Fig. 2

components of the vehicle and trailer involved in the anti-brake trailer brake according to Fig.1 including the associated electro-hydrostatic connections,

Fig. 3

a proposed dependency of the trailer braking of the deflection of the brake control element of a proposed vehicle according to Fig. 1 in a very schematic view.

The proposed vehicle 1 can be used in a variety of applications, especially in the field of agricultural machinery. The example counting in the introductory part of the description may be referred to.

The proposed vehicle 1 is equipped with a hydrostatic drive 2 and with a service brake 3. The hydrostatic drive 2 is used primarily for the propulsion of the vehicle 1, but can also be used for the supply of hydraulic implements application. By means of the service brake 3, the vehicle 1 can if necessary be decelerated to a standstill. The service brake 3 is preferably a hydraulically actuated friction brake. Alternatively, the service brake 3 but also at least partially work pneumatically.

In the traction drive train, the traction drive 2 has a hydrostatic transmission 4 which, in a manner known per se, has a hydrostatic pump 5 on the drive side and a hydrostatic motor 6 on the output side, which are arranged in a closed hydrostatic circuit. The Hydrostatpumpe 5 is here and preferably driven by a diesel engine, not shown. In principle, the hydrostatic transmission 4 can also have more than one hydrostatic pump 5 and more than one hydrostatic motor 6.

According to the proposal, the hydrostatic transmission 4 provides the function of an inching brake, which in any case can also be actuated separately from the service brake 3. The inch braking is, as explained above, to a change in the speed ratio of the hydrostatic transmission 4 and thus back to the braking effect of the diesel engine, not shown. The Inchbremsung can thus be implemented largely control technology with appropriate adjustability of the Hydrostatpumpe 5 of the Hydrostatmotors 6. It is different in the service brake 3, which is as mentioned above regularly a hydraulically or pneumatically operated friction brake.

The separate operability of the inch brake is advantageous, for example, when descending down hills, since the inch braking is largely wear-free. However, inch braking does not provide a "point-to-point" stoppage of the vehicle, so the combined realization of inching braking and service braking has become established in practice. In the Fig. 1 and 2 indicated is the fact that a trailer 7 can be coupled to the vehicle 1, wherein the trailer 7 is one of the vehicle 1 has actuated trailer brake 8. The trailer brake 8 is - as in the service brake 3 - regularly to a hydraulically or pneumatically actuated friction brake.

It is essential that, at least in a predetermined operating mode and coupled trailer 7 inch braking as such triggers a predetermined trailer braking.

The term "inching braking" is to be understood in the manner explained above. In particular, it also includes a user-side inching operation, which will be explained later. In this context, however, it should be noted that the inching braking in question does not necessarily have to be triggered by the operator. It is conceivable, for example, that the inching braking can be purely control technology, especially in the context of a cruise control function.

Preferably, the inch brake trailer brake is at least phased in a substantially proportional relationship to the initiating inch braking, which also appears appropriate in view of the avoidable postponement of the trailer to the vehicle as discussed above. Specifically, it is here and preferably that an operator action to be explained, ie the degree of inching, forms the basis for the above proportional relationship.

In principle, it can be provided that the proposed function of the inch brake trailer brake is permanently activated. It is also conceivable that this function is activated only in a predetermined operating mode of the vehicle 1. For this purpose, for example, a mode switch could be provided, which is operable on the operator side. It is also conceivable that the predetermined operating mode is automatically adjusted by control technology, for example, always after starting the vehicle.

As much as possible to prevent the trailer 7 from being pushed onto the vehicle 1, it is preferred that inch braking, preferably the operator-side inching operation, as such, trigger trailer braking substantially instantaneously.

It can be according to the representation Fig. 1 take the fact that here and preferably provided a deflectable brake control element 9 for operator side inching, which also serves in a particularly preferred embodiment, the operator-side operation of the service brake 3. In principle, the brake operating element 9 can be a brake lever. For this purpose and preferably, the brake operating element is a brake pedal with a pivotable pedal element 9a.

The brake operating element 9 is assigned an electrical sensor arrangement 10 for sensory detection of the inching operation, here the deflection A of the brake operating element 9. Numerous advantageous variants are conceivable for the design of the sensor arrangement 10. For example, the sensor arrangement 10 may comprise an absolute sensor, in particular in the manner of a potentiometer 10a or of a magnetorestrictive MR sensor, exhibit. Alternatively, the sensor arrangement 10 can also have an incremental sensor, in particular in the manner of a Hall sensor or the like, which interacts with a permanent magnet. In the present case, the sensor arrangement 10 has a potentiometer 10a, which is mechanically coupled to the brake operating element 9 for determining the deflection A.

The inch brake related trailer braking preferably proceeds according to a predetermined transfer function U _i in response to the inching braking. The transfer function U _i is in Fig. 3 indicated and will be explained below.

After the transfer function U _i , an increase in inch braking is always accompanied by an increase in trailer braking. In a particularly preferred embodiment, the transfer function U _{i has} at least one substantially linear component, wherein here and preferably the transfer function U _i is altogether a substantially linear function. Here and preferably this means that the inch brake related trailer braking is substantially proportional to the operator side inching action.

The vehicle is preferably provided with a vehicle controller 11, which may be a central vehicle controller 11 or a vehicle controller subdivided into different decentralized sub-controllers. The vehicle controller 11 is inter alia coupled to the sensor arrangement 10 and triggers a trailer braking according to the predetermined transfer function U _i as a function of an inch braking and possibly in response to a still to be explained service braking. This triggering of the trailer braking takes place here and preferably as a function of the sensor data of the sensor arrangement 10 of the brake operating element 9.

The inching braking itself can result from the fact that the brake operating element 9 is additionally equipped with a hydraulic valve which provides a corresponding coupling to a control input of the hydrostatic pump 9 or of the hydrostatic motor 6. Here and preferably, however, it is the case that the sensor arrangement 10 also converts the inching braking. The logic required for this purpose is implemented in the vehicle controller 11, which carries out a corresponding activation of the hydrostatic pump 5 and the hydrostatic motor 6 based on the sensor data of the sensor arrangement 10.

Due to the fact that the inch brake-related trailer braking is performed in the illustrated embodiment in the vehicle controller 11, the transfer function U _{i in question can} be implemented in a particularly flexible manner. Preferably, a transfer function U _{i is selected} from a number of stored transfer functions and / or a possibly selected transfer function U _{i is} parameterized as the basis for determining the trailer braking to be triggered. It is conceivable here that instead of selecting a transfer function U _i only a single transfer function U _{i is} provided, which is parameterized in each case to the current application. The selection of the transfer function U _i and the parameterization of the transfer function U _i are made as a function of at least one brake-relevant influencing factor.

A preferred variant consists in that a sensor arrangement is provided for sensory determination of the current trailer load and that the vehicle controller 11 evaluates the sensor data of the sensor arrangement as a braking-relevant influencing factor. It is also conceivable that a preferably coupled with the vehicle control 11 adjustment control is provided for user-side adjustment of the current trailer load, the position of the adjustment control is then evaluated as a brake-relevant influencing factor. The adjustment control element, for example, in the essential positions, for example in the positions "empty", "half", "full" be brought. It is also conceivable that the adjustment control allows a stepless adjustment.

In the Fig. 1 shown embodiment of the brake control element 9 ensures that a user-side service braking by means of the brake control element 9 always preceded by an inch braking and thus a proposed, corresponding trailer braking. Before the potentially strong service braking is thus always a braking of the trailer 7 instead, which advantageously counteracts the undesirable pushing the trailer onto the vehicle.

The detailed view according to Fig. 1 indicates that the brake operating element 9 can be deflected about a first deflection range A _IB and via a second deflection range A _BB, wherein the deflection ranges A and _IB A _BB adjoin each other.

A deflection A of the brake operating element 9 over the first deflection range A _IB here is an inching operation, with a further deflection A of the brake operating element 9 over a second deflection range A _BB , here and preferably in addition to the inching operation, representing an actuation of the service brake 3 , In any case, a deflection of the brake operating element 9 in both deflection ranges A _IB , A _{BB is in} any case an inching operation.

With the above embodiment of the brake operating element 9 so inch operation is possible without the service brake 3 is actuated. This is advantageous if particularly sensitive braking operations are to be carried out or if, as mentioned above, the descent of a gradient is to be slowed down. Advantageously, the inch braking and possibly the service braking are respectively in a predetermined relationship to the deflection of the brake operating element 9. Preferably, transfer functions with a substantially linear portion are here to be carried such that with increasing deflection A of the brake operating element 9 in particular proportionally increasing inch braking or service braking takes place.

Now interesting is the fact that in a preferred embodiment, the trailer braking is triggered not only by an inch braking, but also by a service brake. In a particularly preferred embodiment, it is now so that the service brake related trailer braking is triggered largely independent of the inch brake trailer brake. This relationship results from the illustration according to Fig. 1 , A first deflection of the brake control 9 acts according to function arrow 12 on the hydrostatic transmission 4, so that an inch braking takes place. The Inchbetätigung acts but not only on the hydrostatic transmission 4, but also on the trailer brake 8, which in Fig. 1 is indicated by the function arrow 13.

A further deflection of the brake operating element 9 beyond the deflection range A _IB is additionally an actuation of the service brake 3 here. This is indicated by the function arrow 14. The service brake 3 in turn acts in a manner yet to be explained and regardless of the inch brake on the trailer brake 8, which is indicated by the function arrow 15 results.

Preferably, the service brake related trailer braking and the inch brake related trailer braking are due to different supply circuits. By "supply circuit" is meant the particular arrangement which provides the braking energy required for trailer braking. The supply circuit is preferably at least partially a hydraulic or pneumatic supply circuit.

In the event that both the service brake 3 and the trailer brake 8 are designed as hydraulically actuated friction brakes, it is in a particularly simple to implement embodiment, that for the service brake related trailer braking the brake circuit 8a of the trailer brake 8 to the brake circuit 3a of the service brake. 3 is coupled, and here the coupling is preferably provided unidirectionally from the brake circuit 3a of the service brake 3 to the brake circuit 8a of the trailer brake 8 out. This unidirectional coupling is in the in Fig. 2 illustrated embodiment realized by a check valve 16.

For the inch brake related trailer braking the brake circuit 8a of the trailer brake 8 is coupled to one of the service brake 3, in particular from the brake circuit 3a of the service brake 3, separate supply circuit 17, wherein here and preferably the separate supply circuit 17 is assigned to the working hydraulics of the vehicle. It is also conceivable that here is a hydrostatic circuit application, for example, a fan o. The like. Provided. Alternatively or additionally, it may be provided that the separate supply circuit 17 has its own hydrostatic pump o. The like. In all cases it is in a simple variant such that the separate supply circuit 17 provides a hydraulic pressure P _I , which is coupled via a proportional pressure relief valve 18 and a check valve 19 to the brake circuit 8a of the trailer brake 8.

The proportional pressure relief valve 18 is connected via an electrical coupling 20 with the vehicle controller 11 so that the loading of the brake circuit 8a of the trailer brake 8 with supply pressure P _I according to the above-mentioned transfer function U _i can be accomplished.

Fig. 2 also shows how the brake control element 9 acts on the here a potentiometer 10a having sensor assembly 10, wherein the potentiometer 10a is coupled via an electrical coupling 21 to the vehicle controller 11.

From the above-mentioned downstream operation of the service brake 3 after the inch brake results in the Fig. 3 _A trailer brake b _A as a function of the deflection A of the brake control element 9. The deflection A is the current deflection angle of the pedal element 9 a, while it is at the trailer braking b _A by a value for the currently provided by the trailer brake 7 brake Torque acts.

In the deflection range A _IB is only an inch braking, which takes place here and preferably in proportion to the deflection A. At the same time, the inching braking leads to a trailer braking b _A , which in the case of Fig. 3 represented diagram goes back to a linear transfer function U _i . Upon deflection of the brake operating element 9 beyond the deflection range A _IB , the service brake 3 additionally comes into operation here and preferably in addition. Among other things, by the here and preferably additionally acting, service brake related trailer braking results in a steeper curve overall, as shown in the illustration Fig. 3 is apparent.

Interesting in the presentation according to Fig. 3 is the fact that a family of curves U _{i is shown} with i = 1,2,3,4. This means here that depending on the trailer load a different transfer function U _i is used. Advantageously, a correspondingly steeper transfer function U _{i is} provided at higher trailer load. Noteworthy is the in Fig. 3 steepest transfer function U ₄ , in which the trailer brake 7 goes into a kind of saturation, even before the service brake 3 comes into action. The selection or parameterization of the respective transfer function U _i by the vehicle controller 11 has already been mentioned above.

According to another teaching, which also has independent significance, a truck 22 is claimed with a proposed vehicle 1 and at least one trailer 7 coupled to the proposed vehicle 1. All versions of the proposed vehicle may be referred to.

According to another teaching, which also has independent significance, a method for the operation of a proposed vehicle 1 with a hydrostatic drive 2 and a service brake 3 is claimed. In this regard, reference may be made to all statements on the operation of the proposed vehicle 1.

LIST OF REFERENCE NUMBERS

1

vehicle

2

hydrostatic drive

3

service brake

3a

brake circuit

4

hydrostatic

5

hydrostatic pump

6

hydrostatic

7

pendant

8th

trailer brake

8a

brake circuit

U

transfer function

9

Brake control element

10

sensor arrangement

10a

potentiometer

11

vehicle control

12,13,14,15

arrows

16

Check valve brake

17

pOWER sUPPLY

18

proportional valve

19

check valve

20

electrical coupling

21

electrical coupling

22

articulated lorry

Claims (15)

Vehicle with a hydrostatic drive (2) and a service brake (3), wherein the traction drive (2) in the drive train comprises a Hydrostatgetriebe (4), wherein the Hydrostatgetriebe (4) provides the function of an inching brake, wherein the inch brake in any case also separately from the Operating brake (3) is actuated and wherein a trailer (7) with a vehicle from the (1) actuated trailer brake (8) to the vehicle (1) can be coupled,
characterized,
as such, at least in a predetermined operating mode and with the trailer (7) coupled, initiates a predetermined trailer braking. A vehicle according to claim 1, characterized in that the arrangement is such that the inch brake related trailer braking is at least in phase in a substantially proportional relationship to the initiating inching, preferably to a corresponding operator side inching operation. Vehicle according to claim 1 or 2, characterized in that a deflectable brake operating element (9), in particular a brake lever or a brake pedal, for operator side Inchbetätigung and possibly to the user-side actuation of the service brake (3) is provided, preferably that the inch brake related trailer braking at least phased in a substantially proportional relationship to the deflection (A) of the brake control element (9). Vehicle according to claim 3, characterized in that associated with the brake operating element (9) is an electrical sensor arrangement (10) for sensory detection of the deflection (A) of the brake operating element (9), preferably in that the sensor arrangement (10) comprises an absolute sensor , in particular in the manner of a potentiometer or an MR sensor, or that the sensor arrangement (10) has an incremental sensor, in particular in the manner of a Hall sensor or the like. Vehicle according to claims 3 and optionally according to claim 4, characterized in that an electric vehicle control (11) is provided, which is coupled to the sensor arrangement (10) and the trailer braking according to a predetermined transfer function (U _i ) in response to a Inch braking and possibly in response to a service brake, in particular in response to the sensor data of the sensor assembly (10) triggers. Vehicle according to claim 5, characterized in that the vehicle controller (11) selects a transfer function (U _i ) from a number of stored transfer functions (U _i ) as the basis for the determination of the trailer braking to be triggered as a function of at least one brake-relevant influencing factor and / or parameterization the possibly selected transfer function (U _i ) makes. Vehicle according to claim 6, characterized in that a sensor arrangement (10) for sensory determination of the current trailer load or a setting control is provided to the operator side setting the current trailer load and that the vehicle controller (11) evaluates the sensor data of the sensor assembly (10) or the position of the adjustment control element as a brake-relevant influencing factor. Vehicle according to claim 3 and optionally according to one of claims 4 to 7, characterized in that a user-side service braking by means of the brake control element (9) always preceded by an inch braking and thus a corresponding trailer braking. Vehicle according to claim 3 and optionally according to one of claims 4 to 8, characterized in that a deflection of the brake operating element (9) over a first deflection range (A _IB ) is an inching operation and that a further deflection of the brake operating element (9 ) over a second deflection range (A _BB ), preferably in addition to the inching operation, is an operation of the service brake (3), preferably that a deflection of the brake operating element (9) in both deflection ranges (A _IB , A _BB ) is in any case an inching operation is. Vehicle according to one of the preceding claims, characterized in that a service brake as such triggers a predetermined trailer braking and that the service brake related trailer braking is triggered independently of the inch brake related trailer braking. Vehicle according to one of the preceding claims, characterized in that the service brake related trailer braking and the inch brake related trailer braking go back to different supply circuits. Vehicle according to one of the preceding claims, characterized in that for the service brake related trailer braking with coupled trailer (7) of the brake circuit (8a) of the trailer brake (8) to the brake circuit (3a) of the service brake (3) is coupled, preferably that the coupling is provided unidirectionally from the brake circuit (3a) of the service brake (3) to the brake circuit (8a) of the trailer brake (8) out. Vehicle according to one of the preceding claims, characterized in that for the inch brake related trailer braking the brake circuit (8a) of the trailer brake (8) to one of the service brake (3), in particular from the brake circuit (3a) of the service brake (3), separate supply circuit (17 ), preferably, that the separate supply circuit (17) is assigned to the working hydraulics of the vehicle, and / or that the separate supply circuit (17) has its own Hydrostatic pump. Truck with a vehicle (1) and at least one to the vehicle (1) coupled trailer (7), preferably with a vehicle (1) according to one of the preceding claims, wherein the vehicle (1) a hydrostatic drive (2) and a service brake (3), wherein the traction drive (2) in the traction drive train has a hydrostatic transmission (4), wherein the hydrostatic transmission (4) provides the function of an inching brake, the inching brake in any case also separate from the service brake (3) is actuated and wherein the trailer (7) has a trailer brake (8) which can be actuated by the vehicle (1),
characterized,
As such, at least in a predetermined operating mode, inch braking triggers a predetermined trailer braking. Method for operating a vehicle (1) having a hydrostatic drive (2) and a service brake (3), preferably a vehicle (1) according to one of claims 1 to 13, wherein the travel drive (2) in the drive train is a hydrostatic transmission (4). In any case, the inching brake can also be actuated separately from the service brake (3), and a trailer (7) with a trailer brake (8) which can be actuated from the vehicle (1) is attached to the Vehicle (1) is docked,
characterized,
that at least in a predetermined operating mode and when the trailer (7) is coupled by an inch braking as such, a predetermined trailer braking is triggered.

Images